Tetracarboxyalkyl orthosilicates

ABSTRACT

BUILDERS FOR USE IN SYNTHETIC DETERGENT COMPOSITION ARE DESCRIBED; SAID BUILDERS COMPRISING REACTION PRODUCTS OF SILICO TETRAHALIDES AND HYDROXY SUBSTITUTED CARBOXYLIC ACIDS.

- U.S. Cl. 260448.8 R

United States Patent ABSTRACT OF THE DISCLOSURE Builders for use in synthetic detergent compositions are described; said builders comprising reaction products of silicon tetrahalides and hydroxy substituted carboxylic acids.

The present invention relates to particular silicon containing compounds derived from hydroxycarboxylic acids or their salts and their use as builders for detergents compositions. In a further aspect, the invention relates to improved detergent compositions and an improved process for washing fabrics in an aqueous medium containing detergent compositions which are combined with such builders.

It is well known to those skilled in the art, to improve the detergency effectiveness and whitening powder of synthetic detergent compositions by incorporating detergent builders, therein. Heretofore polyphosphate compounds such as, for example, sodium tripolyphosphate have been widely used as builders. Such compounds are particularly useful because of their relatively low cost and utility in increasing the whitening power of detergent compositions containing them. But it is also postulated that the presence of the polyphosphates tend to accelerate the growth of algae in lakes and rivers to a sufiicient degree whereby the natural ecology of these waters is significantly upset. With the recent governmental emphasis on better control of environmental conditions, pollution such as that caused by the discharge of phosphate containing wash waters into waterways is being more closely watched and studied. There is increasing pressure to discontinue or substantially decrease the amount of phosphate in detergent compositions in favor of non-phosphate builders.

The manner in which detergent builders improve the whitening powers of detergent compositions is related to a combination of factors. Thus, builders are believed to improve detergent washing efiiciency by affecting the emulsification of the soil particles, solubilization of the water insoluble materials, promoting solid suspension in the wash water so as to retard soil redeposition, sequestering of the metallic ions, and the like.

Among the important properties that must be exhibited by compounds employed as builders are included: the ability to increase the whitening power of the detergent composition, nontoxicity, compatibility with the various components of conventional detergent compositions, and stability with respect to hot alkaline, aqueous mediums and bleaching agents.

It is the prime object of this invention to provide a non-phosphate builder which is particularly effective in increasing the Whitening power of synthetic detergent compositions. It is a further object of this invention to provide a method for washing fabrics in a medium containing a non-phosphate builder. Various other objects and advantages of this invention will be apparent from the following description thereof.

I have now discovered that certin tetraalkoxysilanes are useful. as builders, in aqueous detergent compositions. These tetraalkoxysilanes are characterized by the presence of an alkyl group which has substituted thereon one or more carboxylic acid groups or the salts thereof. Such organo-silicon derivatives of the type contemplated for used n he present invention are not commercially avail- 3,806,533 Patented Apr. 23, 1974 able but may be prepared by either of the following preferred methods:

(1) by the reaction of an hydroxy-substituted carboxylic acid with a silicon tetrahalide in the presence of an organic solvent followed by, if desired, treatment with a base to form the corresponding salt, or

(2) by the direct rection of the salt of an hydroxy-substituted carboxylic acid with a silicon tetrahalide in the presence of an organic solvent to obtain the salt of the respective orthosilicate.

In accordance with method 1, supra, a typical reaction of a mono-hydroxy compound may be schematically represented as follows:

wherein R is a polyvalent, paraffin radical having l-3 carbon atoms, and n is an integer from 1 to 3 but not greater than the number of carbons in R with each carbon having no more than one carboxyl group attached thereto.

The exact composition of the products formed by the reaction of a polyhydroxy-substituted monoor polycarboxylic acid with silicon tetrahalides is not known with certainty. However, the practitioner will recognize the possibility of the formation of certain cyclic compounds, as well as polymeric structures, wherein the molecule has more than one silicone atom present. The polyhydroxycarboxylic acids (each carbon having no more than one hydroxy group attached thereto) and the silicon tetrahalide are reacted at concentrations of between 1 and 2 moles of acid to one mole of silicon tetrahalide. A stoichiometric amount of acid is required such that the total number of functional hydroxy groups in the acid is equal to the total number of halogen groups in the silicon tetra= halide. For example, one mole of a tetrahydroxy-substituted acid and two moles of a dihydroxy-substituted acid respectively, are reacted with one mole of a silicon tetrahalide. Accordingly, it is on this basis that the reactions for the preparation of the present tetraalkoxy silanes are controllably conducted under the conditions discussed hereinafter.

Such programmed reactions are carried out at tempera= tures ranging between 40 and C. over periods up to several hours. Reaction times will vary with such factors as the reactivity properties of the particular ingre dients involved and the temperature. Subsequent to the reaction according to method 1 described above, the neutralization of the product obtained thereby is ordinarily carried out at about 25 C. over a period of from 1 to 4 hours.

As previously indicated, starting materials may include monoor poly-hydroxy-substituted monoor polycarboxylic acids in the one instance or the alkali metal or ammonium salts of the acids in the second. But in either in stance, the silicon tetrahalide reagent, may be silicon tetrabromide, tetraiodide or preferably tetrachloride.

Among the hydroxy-carboxylic acids which are suitable for the preparation of the orthosilicate derivatives according to method 1 herein and useful in practice of this in vention are glycolic, lactic, citric, tartaric, malic and saccharic acids. The carboxylic acid derivatives can then be converted by conventional methods into ammonium salts, alkali metal salts, amine salts, or alkanolamine salts prepared from low molecular weight amines, preferably with molecular weights below about 300.

Suitable salts for the preparation of similar orthosilicates according to method 2 described above, are those derived by conventional methods such as the neutralization of any of the aforesaid acids whereupon the salt produced thereby is that having, as a cation, an alkali metal or a structure which contains nitrogen and the molecular weight of the same does not exceed 300. In general, the alkali metal salts, particularly those of sodium and potassium, are preferred for the preparation of the novel, detergent builders of the present invention.

Suitable organic solvents for the preparation of the silicon derivatives herein include benzene, chloroform, n-decane, and, inter alia, pyridine. However, it is preferred that n-heptane or benzene be used as a solvent in the reactions of the hydroxycarboxylic acid or salt thereof with the silicon tetrahalide.

The preferred detergent builder of the type embodied in this invention is the water-soluble tetracarboxymethyl orthosilicate formed when sodium glycolate is reacted with silicon tetrachloride in the presence of benzene at 80 C. over a period of two hours. Such compounds are resistant to the action of water, yet soluble without decomposition in an alkaline medium, while capable of enhancing the whitening power of the detergent agent in a detergent, wash composition. Also, the water solubility of such detergent builder should be at least 0.1 gram per 100 grams of water at 25 C.

In the practice of this invention it is preferred that the detergent composition be formulated so that the subsequent aqueous washing solutions prepared therefrom have pH values between 7.0 and 13.0. Since most conventional, synthetic detergent compositions are employed in alkaline systems, the acidic compounds obtained, using method 1 hereinabove, may be utilized more efiiciently by adjusting the pH of the resulting detergent composition to yield the desired pH value in the final washing solution.

It is an advantage of the present builders that in addition to enhancing the whitening power of detergents to a degree comparable to sodium tripolyphosphate, they are fully compatible with and stable toward bleaching agents commonly used in conventional clothes washing. Thus, the detergent builders of the present invention neither lose their whitening power in the presence of bleaches such as chlorine bleaches nor do they interfere with or impair the function of the bleaches themselves.

In utilizing these detergent builders, they are most conveniently admixed with a selected detergent composition in place of (either partially or entirely) the conventional builder as, for example, sodium tripolyphosphate. Ordinarily conventional, commercially available detergent compositions will contain from less than about 1% up to about 60% or more of builder, based on the weight of the total detergent composition solids (the remainder comprising synthetic organic detergent and auxiliary compounds) and it is comprehended that the present novel builders may be utilized in the same concentrations. Concentrations of builder within the range of from about 20 to 60%, based on the weight of the total detergent compositions, are preferred, however, since builder concentrations of less than about 20% will usually result in insutficient whitening power. In utilizing the novel builders it is to be understood that the detergent composition incorporating the builder can be prepared for use in any of several physical forms, as for example, granular, flake, bar, tablet and liquid forms.

If desired, however, the selected builder of our invention can be added to the wash media separately with equal effect. The detergent composition, in addition to the detergent and builder, may also contain a number of other ingredients. Thus, the detergent composition may contain any of the usual types of fillers, such as sodium sulphate, sodium carbonate and the like in the customary amounts. Anticorrosion agents such as sodium silicate and sodium metasilicate as well as optical brighteners, soil anti-redeposition agents, and enzymes may also be included, if desired, in amounts which are entirely conventional and known to those skilled in the art.

The builder described herein may be utilized in a detergent composition comprising any of the synthetic organic detergents which are commonly used for aqueous washing purposes. The detergent may be of the anionic,

non-ionic, cationic, or amphoteric type or character. Further description of detergents such as are useful in the detergent compositions comprehended herein are readily found in the literature, as for example, in US. Pat. 2,755,252 entitled Partially Acetylated Polyvinyl Alcohol as a Soil-suspending Agent issued July 17, 1956 and US. Pat. 3,459,670 entitled Builders for Synthetic Detergents issued Aug. 5, 1969 which are incorporated herein by reference. It is clear that the particular detergents used in the detergent compositions of the present invention is not critical except that it should be generally useful in emulsifying and detergent applications.

The actual use of the detergent builders of this invention comprises the use of the resultant detergent composition (detergent, builder and optional additives) in conventional concentrations, i.e. from about 0.1 to 0.2%, based on the weight of the wash water, in a conventional washing procedure, ordinarily making use of agitation and temperatures ranging up to about 180 F. Use of the detergent composition in this manner has been found to enhance the whitening power of the wash medium, and the fabrics washed therewith have been found to be significantly brighter.

The invention is further illustrated in connection with the following examples in which all parts given are by weight unless otherwise noted. The water employed in the wash media as well as the rinses in all of the following examples was adjusted to have a hardness of about 150 ppm. measured as calcium carbonate.

EXAMPLE I This example shows the preparation of a novel detergent builder of the type derived from the reaction product of a silicon tetrahalide and a hydroxycarboxylic acid which is subsequently reacted with an alkali metal base.

Using method I referred to, a builder was prepared as follows:

(A) Into a reaction vessel containing 30.4 g. of glycolic acid in ml. of n-heptane there was introduced under moderate stirring 17.0 g. silicon tetrachloride. The temperature of this mixture was kept at about 25 C. for one hour. Then the mixture was refluxed for two hours and cooled. Thereafter the heptane was decanted, and the insoluble, waxy tetracarboxymethyl orthosilicate product was dried by heating at 45 C. under vacuum. The yield of said product was 27.7 g.

(B) A suspension of about 5.0 g. of the product pre pared in (A) in 100 ml. of water was then neutralized to a pH of 11.5 by the addition of a sutficient quantity of a, 10 percent sodium hydroxide solution. The subsequent re action was complete in four hours. The pH of the resultant solution was then adjusted to 7.5 with a 50 per cent sulfuric acid solution. Thereafter the water was removed by heating under vacuum, and the dry sodium salt of the tetracarboxymethyl orthosilicate obtained therefrom was used, as a builder in the following compositions labeled as samples A and C:

As indicated by the chart, the compositions of B and D are typical of those of conventional detergents having polyphosphate builders therein at the respective concen trations, and E is a control without a builder.

A series of aqueous wash media were prepared by ad mixing 1.5 grams of each of the five above described detergent compositions, respectively, to 1000 milliliters of water. Swatches (3" by 7") of unsized, undyed cotton were soiled in a small test area measuring about 1%" in diameter by wiping the skin of the brow, hands, and neck of each member of a test panel of male individuals, respectively, in an effort to approximate the soiling of fabrics which takes place in day-to-day situations. Each wash load contained a swatch from each panel member. The washes were conducted in a Washing apparatus sold by US. Testing Company and called a Terg-o-Tometer with the temperature of the wash media at 120 F. The washed swatches were rinsed and ironed between two pieces of white fabrics so as to eliminate any dirt transfer from the iron. Reflectance readings indicating the degree of whiteness of the test area were then made with a Photovolt Corportaion Photoelectric Reflectance Meter, Model 610. Thereafter, the test procedure, including the soiling of the idenci'al test areas of each swatch, respectively, was repeated four times. Reflectance readings of the test swatches with and without soiling before washing were also obtained and the readings were appropriately inserted into the following equation in order to obtain the Percent Detergency of the test composition.

Percent detergency g (100) where:

R =reading of washed, solied swatch, R =reading of unwashed, soiled swatch, R =reading of unsoiled swatch.

Table I summarizes the results obtained with the various indicated wash media. Each of the percent detergency values given in the table is the mean of ten swatches.

TABLE I Percent detergency after Wash N 0.- Percent Composition builder 1 2 3 4 5 A-.- 40 86 88 87 7 B 79 B 40 100 93 86 87 87 95 85 82 78 77 It is seen from the above data that the detergent compositions containing the novel builder of this invention exhibit percent detergency values comparable to those achieved with compositions containing a conventional, commercially used builder, namely sodium tripolyphosphate. Also it is to be noted that the novel detergent compositions containing builders yielded substantially better percent detergency values than those obtained with a de tergent composition containing no builder at all.

EXAMPLE II This example shows the usefulness of a novel detergent builder of the type derived from the reaction of a silicon tetrahalide with an alkali metal salt of a hydroxycarboxylic acid which was prepared according to method 2 above as follows:

Into a reaction vessel containing 39.2 g. of sodium glycolate in 100 ml. of benzene there was introduced under slow stirring 17.0 g. of silicon tetrachloride. The slurry was stirred for one hour and then refluxed for two hours. Thereafter the benzene was removed by heating at 50 C. under vacuum. The yield of the dry sodium salt of tetra= carboxymethyl orthosilicate was 42.7 grams.

Using the detergency evaluation procedure set forth in Example I, additional soiled and unsoiled swatches were evaluated following washings in a test detergent solution, A or C, or a standard control solution, B or D. Accordingly, the test solutions contained the above described compound, and the control solutions sodium tripolyphosphate, as builders, at the respective concentrations employed in the aforesaid example. Results are summarized in Table II. Thus, it is shown by the data below that the detergent compositions containing a novel builder prepared by an alternate method contemplated in this invention also exhibit percent detergency values comparable to those achieved with compositions containing a com mercial builder.

TABLE II Percent detergency alter Wash No.

Percent Composition builder 1 2 3 4 5 EXAMPLES III-VI These examples illustrate the builder effectiveness of additional salts of orthosilicate derivatives prepared according to method 1 described above, using various hydroxycarboxylic acids. In these instances steps A and B of Example I were repeated, except the particular acid in the organic solvent and the silcon tetrachloride where reacted at the concentrations set forth in the chart below.

Tartaric acid. n-Heptane (rnL) Silicon tetrachloride Test detergent compositions similar to that of A in Example I were prepared, except in each of the instant compositions 40 parts per 100 parts of one of the respective derivatives described above was used as a builder, in lieu of the sodium salt of the tetracarboxymethyl orthosilicate. Using a standard detergent formulation similar to that of B in Example I having a polyphosphate builder therein as a control, the eflectiveness of the builders in the test compositions were determined by the procedure employed in the said example. Results, thus obtained, are presented in Table III below.

TABLE III Percent detergency alter Wash No.- Percent Builder No builder 1 2 3 4 Composition:

E I 40 73 74 66 F II 40 95 86 84 G. III 40 9O 71 69 74 H IV 40 90 84 73 68 Control. 40 93 85 82 71 This example illustrates a typical detergent composition being used in a wash medium containing a chlorinereleasing bleach.

Two detergent compositions were prepared, one identical to the test composition A of Example I and the other identical to the control composition B containing builder described in Example I. The compositions were evaluated as described therein with the sole exception that the wash media had added thereto a chlorine-releasing bleach in a concentration equal to 0.033%, by weight, of active chlorine. The results indicated there was no breakdown of the builder in the presence of the bleach or impairment of the bleaching function. It was also indicated that based on the percent detergency evaluations, builder effectiveness of the test composition was comparable to that of the control.

7 8 Summarizing, it is seen that this invention provides a 3. A composition of matter selected from the group novel, effective class of nonphosphate builders for use in consisting of preparing detergenthcompositions. h d (a) compounds having the formulas It is to be noted t at although emp asis has been place in describing this invention in connection with the wash- SI(OCHZ CQOH) ing of fabrics, the detergent compositions comprehended within the scope of the invention are likewise useful for m-COOH 4' all washing purposes including, for example, dishwashing, and floor washing, car washing, and the like. Variations in ma- (coom cm coon terials, proportions, and procedures may be made without 10 departing from the scope and spirit of this invention as HPCOOE 4 defined by the following claims. and

Iclaim: (b) the fully and partially neutralized alkali metal, 1. As a composition of matter a compound selected ammonium, amine, and l an l m e sa ts f lai from the group consisting of: compounds.

(a) the reaction products of a hydroxy carboxylic acid selected from the group consisting of tartaric acid and Reference! cited saccharic acid, and a stoichiometric amount based UNITED STATES PATENTS on the number of hydroxyl groups, of a Silicon tetra- 2,486,993 11/1949 Sowa n 260 8.8 R x halide selected from the group consisting of silicon 2O tetrachloride, silicon tetrabromide and silicon tetra- DANIEL EWYMAN primary Examimr iodide, and I u (b) the fully and partially neutralized alkali metal, SHAVERIASSIStam Exammel' ammonium, amine, and alkanolamine salts of said reaction products.

2. The sodium salt of the tetraester of orthosilicic acid 252-; 260-448.8 A

and glycolic acid, 

